Tellurium resistor for refrigerators



Sept. 27, 1932. E. H. HORSTKOTTE TELLURIUI RESISTOR FOR REFRIGERATORSFilod March 3. 1930 Inventor: Edward H. Horabkotbd b Wm His Abborng 7 K/I i Patented Sept. 27, 1932 UNITED. STATES rarsm'q-o'rrlcs EDWARD K.'HOBSTKOTT'E, OF SCHENECTADY, NEW YORK, ASSIGHOB TO Gm ELECTRIC COMPANY,A CORPORATION OF YORK 'rmmumuu usls'roa ron mnmnm'roas Application illedlarch 8, 193). Serial No. 482,720.

My invention relates to electrical resistors and provides an improvedresistor of the sir called self-reducing type; that is, one which hassuch a high negative temperature efficient that its initial resistanceis reduced to a relatively low value when its temperature is raised asby the heating efiect of a current passing therethrough. My presentinvention is an improvement over the device set forth and claimed inapplication No.

384,7 56, to Clifford A. Nickle, filed August 9, 1929, and assigned tothe same assignce.

This application has since matured to Patent 7 In a device ofthis'character it is highly desirable to have a. unit which may bereadily inserted in a circuit or removed therefrom so that replacementis made quite an easy process. Tellurium is an ideal material for aresistor having a negative temperature coeflicient. Due to the inabilityto draw this material into a resistor wire with any degree of success,it has been found necessary to cast it within a mould-such as a base ofinsulating material. The materials usually used for this purpose,however, permit the tellurium to heat up too rapidly. Porcelain wasfinally selected because due to its heat storage capacit it will absorbsome of the heat which otherwise would tend to heat the tellurium andthus reduce its resistance too rapidly. It has been found however thatwhen tellurium alone is used as a resistor, and is cast within aporcelain base, the tendency of the resistor is to still drop inresistance too quick- 1y for many practical purposes. Again-if thecircuit in which the self-reducing resistor is placed is opened andimmediately closed, if the resistor has a low value of resistance due toheat from current carried for an appreciable length of time, it will ofcourse fail in its function of limiting the initial current through thecircuit. Some means, therefore,

is desirable for providing a minimum value of resistance for sucharesistor. Another It is a general object of my invention to fixed valueon the surface, the tellurium re-' sistor and the fixed resistor. beingplaced in l I series. The arrangement .of the resistors upon the baseresults in a compact unit A screw means is mounted upon the base makingthe device readily replaceable as a unit by being screwed into a socketcooperatin lurium as a natural characteristic such with said screwmeans. The telthat upon being heated by a current flowing therethroughthe value of the resist ance decreases. The purpose of the secondresistor in series with the tellurium resistor is to provide aminimumvalue of resistance for the resistor unit.

My invention will better understood from the following descri tion whenconsidered in connectionwith t e accompanying drawing and its scope willbe pointed out the appended claims.

Fig. 1 shows a side view ofmy invention Fig. 2 shows a cross sectionthereof; Fig. 3 shows the application of my invention to a motorcircuit. I v

Referring to Fig. 1 the resistor consistsof a base 10 of insulatingmaterialprovided with grooves therein in which the resistor 11 is wound.The base. of the resistor is pro- .vided with the screw member 12 whichwill fit a screw socket.

In Fig. 2 it will be seen that the base 10 has provided therein aU-shaped passageway which is filled with a self-reducing resistormaterial such as tellurium. This self-reducing resistor element 14 isconnected in series with the other resistor 11 by means of the member13. The other endof the resistor 11 is connected to the screw threadedmember 12, as shown in Fig. 1. The resistor 11 has a substantiallyconstant value under substantially all operating conditions. Thus, itdue to a large current flowing through the tellurium resistor 14, itsvalue should be decreased to a large extent, the minimum resistance ofthe resistor unit will always be greater than the value of the resistor11 the value of which is substantially constant. It will be noted thatby providing a U-shaped passageway within my insulating base 10, Iprovide a longer resistor unit of tellurium than could otherwise beobtained by merely using a single passageway through the resistor base10 from end to end.

Connected to the button member 18 and insulated from the resistor 14 bymeans of the insulating element 15 is the element 16 connected to theother end of the resistor 14. A slot 17 in the member 10 permits theelement 16to pass by the screw member 12 without contact therewith. Itwill thus be seen that a circuit is completed from the screw member 12through the resistor 11, connecting means 13, resistor 14, connectingmeans 16 to the button member 18. The screw member 12 and the buttonmember 18 make this unit readily applicable to a socket.

In Fig. 3, the application of my invention to an electric controlcircuit for a motor is shown. It will be evident, of course, that myself-reducing resistor may be used in other circuits. In the circuitshown in Fig. 3, a split phase motor is provided with a starting winding24, a running winding 23, and a rotor 22. The self-reducing resistor 10is connected in series with the starting winding 24 to limit thestarting current therethrough. In series with the running winding 23 isthe electroresponsive device 25 which provides a circuit through thestarting winding to start the motor. The switch 26 is for the purpose ofconnecting the motor across the lines 20 and 21. Of course, when theswitch 26 is closed, the running winding 23 and electroresponsive device25 are simultaneously energized thus causing the electroresponsivedevice 25 to close its contacts to energize the. starting winding 24 tostart the motor. The combination of a resistor unit comprising a fixedresistance and a self-reducing variable resistance, and a split-phasemotor as disclosed in Fig. 3, is not a partot my invention but isdisclosed and claimed in a copending application of ChristianSteeristrup, Serial No. 438,858, filed March 25, 1930, and assigned tothe same assignee as the present invention.

In the operation of my device in the case of high or medium appliedvoltages, the value of the resistor is such that the currentflowingthrough the starting winding is sufiicient to start the motor but isstill limited to a value which is not objectionable to cause flickering'of the lights and the like. Thus, the units provide a proper value ofresistance in the case of normal and high applied voltages.

In the case of a low applied voltage, the current flowing through thestarting winding may be insuiticient to provide a starting torque tostart the motor. As the current continues to flow through the resistorunit, the heat causes the resistance of the tellurium resistor 14 toreduce. This permits more and more current to flow through thestartingwinding until such a value of resistance is reached by thetellurium resistor that the resistor unit provides a resistance 'of sucha value that a proper amount of current may flow therethrough to startthe motor. It is understood that the above operation occurs quickly.

It will thus be seen that my device works equally well on low, high andnormally applied voltages to provide a current which is notobjectionable. The unit is compact and readily replaceable.

The embodiment of the invention illustrated and described herein hasbeen selected for the purpose of clearly setting forth the principlesinvolved. It will be apparent, however, that the invention issusceptible of being modifiedto meet the different conditionsencountered in its uses and I, therefore, aim to cover by the appendedclaims all modifications within the true spirit and scope of myinvention. a

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A self-reducing resistor unit for electric circuits having a base ofinsulating material provided with a passage therein, a telluriumresistor filling said passage, said base having relatively high heatstorage capacity for preventing a rapid decrease in resistance of saidtellurium when said resistor unit-is in use, and a resistor ofsubstantially constant value in series with said first telluriumresistor and supported on the outside of said base whereby the unit islimited to a predetermined minimum value of resistance.

2. A self-reducing resistor unit for electric circuits comprising a baseof insulating material having a passage therein, a tellurium resistorfilling said passa c, said base having the characteristic of absor ingheat from said resistor to prevent rapid decrease in resistance whensaid unit is in use, a second resistor having a substantially fixedresistance in series with said tellurium resistor, said second resistorbeing supported on the outside of said base.

3. A self-reducing resistor unit comprising a base of insulatingmaterial having a passage therein. a tellurium resistor filling saidpassage, said base having heat storage capacity whereby a rapid decreasein resistance of said tellurium is prevented when said unit is in use,and a resistor of fixed value in series therewith and supported by saidbase, a screw means for said unit removably supporting base andconnected in series with said tellu-' rium resistor, a screw means forsaid unit for removably supporting said unit within a screw socket, andelectrical connecting means between said means and said resistorswhereby when said unit is mounted within an electric socket saidresistors will be electrically connected to said sockets.

5. A self-reducing resistor unit comprising a base of insulatingmaterial, a tellurium resistor within said base extending from end toend of said base and of substantially U-shape the ends thereofterminating in the surface of said base at one end thereof, a resistorhaving a substantially fixed resistance supported on the outside of saidbase and connected in series with one end of said tellurium resistor forproviding a minimum limit of resistance for said unit, a screw meansmounted at the other end of said base in which said tellurium resistorterminates, said fixed resistor being connected to said screw means anda contact-making means mounted at the same end of said base with saidscrew means but insulated from said screw means and means forelectrically connecting the other end of said tellurium resistor to saidcontact-makin means.

11 witness whereof, I have hereunto set my hand this 1st day of March,1930.

EDWARD H. HORSTKOTTE.

